IT in 1975 (apo to Mythical Man-Month): > Consider the IBM APL interactive software system. It rents for $400 per month and, when used, takes at least 160 K bytes of memory. On a Model 165, memory rents for about $12 per kilobyte per month. If the program is available full-time, one pays $400 software rent and $1920 memory rent for using the program.